libjxl < 0.9.0 is not supported. See https://github.com/libjxl/libjxl/issues/4400

.ci/install.sh

@@ -18,7 +18,7 @@ aptget_update || aptget_update retry || aptget_update retry
 set -e
 
 sudo apt-get -qq install libfreetype6-dev liblcms2-dev libtiff-dev python3-tk\
-                         ghostscript libjpeg-turbo8-dev libjxl-dev libopenjp2-7-dev\
+                         ghostscript libjpeg-turbo8-dev libopenjp2-7-dev\
                          cmake meson imagemagick libharfbuzz-dev libfribidi-dev\
                          sway wl-clipboard libopenblas-dev nasm
 

docs/installation/building-from-source.rst

@@ -97,6 +97,10 @@ Many of Pillow's features require external libraries:
     and decoder, such as rav1e and dav1d, or libaom, which both encodes and
     decodes AVIF images.
 
+* **libjxl** provides support for the JPEG XL format.
+
+  * Pillow requires libjxl version **0.9.0** or greater.
+
 .. tab:: Linux
 
     If you didn't build Python from source, make sure you have Python's
@@ -284,7 +288,7 @@ Build options
   ``-C tiff=disable``, ``-C freetype=disable``, ``-C raqm=disable``,
   ``-C lcms=disable``, ``-C webp=disable``,
   ``-C jpeg2000=disable``, ``-C imagequant=disable``, ``-C xcb=disable``,
-  ``-C avif=disable``.
+  ``-C avif=disable``, ``-C jpegxl=disable``.
   Disable building the corresponding feature even if the development
   libraries are present on the building machine.
 
@@ -292,7 +296,7 @@ Build options
   ``-C tiff=enable``, ``-C freetype=enable``, ``-C raqm=enable``,
   ``-C lcms=enable``, ``-C webp=enable``,
   ``-C jpeg2000=enable``, ``-C imagequant=enable``, ``-C xcb=enable``,
-  ``-C avif=enable``.
+  ``-C avif=enable``, ``-C jpegxl=enable``.
   Require that the corresponding feature is built. The build will raise
   an exception if the libraries are not found. Tcl and Tk must be used
   together.

docs/reference/features.rst

@@ -22,6 +22,7 @@ Support for the following modules can be checked:
 * ``littlecms2``: LittleCMS 2 support via :py:mod:`PIL.ImageCms`.
 * ``webp``: WebP image support.
 * ``avif``: AVIF image support.
+* ``jpegxl``: JPEG XL image support.
 
 .. autofunction:: PIL.features.check_module
 .. autofunction:: PIL.features.version_module

docs/reference/plugins.rst

@@ -169,6 +169,14 @@ Plugin reference
     :undoc-members:
     :show-inheritance:
 
+:mod:`~PIL.JpegXlImagePlugin` module
+------------------------------------
+
+.. automodule:: PIL.JpegXlImagePlugin
+    :members:
+    :undoc-members:
+    :show-inheritance:
+
 :mod:`~PIL.McIdasImagePlugin` module
 ------------------------------------
 

src/PIL/features.py

@@ -15,9 +15,9 @@ modules = {
     "tkinter": ("PIL._tkinter_finder", "tk_version"),
     "freetype2": ("PIL._imagingft", "freetype2_version"),
     "littlecms2": ("PIL._imagingcms", "littlecms_version"),
-    "jpegxl": ("PIL._jpegxl", "libjxl_version"),
     "webp": ("PIL._webp", "webpdecoder_version"),
     "avif": ("PIL._avif", "libavif_version"),
+    "jpegxl": ("PIL._jpegxl", "libjxl_version"),
 }